Hezbollah, backed by Iran, is a key ally of Syrian President Bashar Al-Assad's regime and has deployed fighters to support loyalist troops in the country's civil war.

Hezbollah’s involvement in the Syrian war has resulted in a deep sectarian gulf in Lebanon between Shiites and Sunnis, many of whom support the anti-Assad revolt.

Tehran also accused Israel of carrying out the blasts in Beirut.

The bombings were "an inhuman crime and spiteful act done by Zionists and their mercenaries," Iranian foreign ministry spokeswoman Marzieh Afkham said in remarks carried by the official IRNA news agency.

The attack was the latest in a string of attacks that have struck Lebanon in recent months.

A car bomb hit the southern suburbs of Beirut on July 9, causing no fatalities, and again on August 15, killing 27 people.